1. Field of the Invention
The present invention relates to hairstyling devices in which a first jaw is hinged to a second jaw by hinge means including a return spring.
2. Description of the Prior Art
Hairstyling devices in the form of clips for use in women""s hair are known in the art. Clips of this kind have been used for many years, and are described especially in documents FR-A-770 805, FR-A-755 662 or U.S. Pat. No. 2,201,719.
Prior art hairclips generally have a first jaw and a second jaw, hinged together by hinge means allowing them to pivot about a hinge axis between a spread apart position and a close together position. Spring means bias pivoting relative movement of the first and second jaws toward their close together position. The hinge means comprise two first parallel perforated lugs on the first jaw spaced apart for stability, and, two parallel perforated lugs on the second jaw appropriately spaced apart to engage with respective opposite sides of the first perforated lugs. A connecting spindle, oriented along the hinge axis, passes through the four perforated lugs to connect the jaws.
In these prior art hairclips, the spring means comprise an elastically flexible metal wire spring wound helically around the hinge axis. A first end of the elastically flexible wire extends radially away from the axis and bears on the inside face of the first jaw. The second end of the elastically flexible wire extends radially away from the axis and bears against the second jaw. The spring is prestressed rotationally about the axis, so that its two projecting ends bias the jaws toward their close together position.
A first disadvantage of the above prior art structure is the result of the particular use of the hairstyling devices, whereby their rear part, which is the part consisting of the hinge area and the elastically flexible metal wire wound in a helix, can be seen when they are placed in the hair. This produces a particularly unesthetic effect, because the structure of the elastically flexible metal wire spring is clearly visible and gives the appearance of a mechanical device to a hairstyling device that in theory should constitute an ornamental item.
Another important disadvantage of the above prior art structure is the difficulty of fitting the prestressed spring. The four components, namely the two jaws, the spring and the connecting spindle, have to be assembled at one and the same time, while applying an appropriate force to the spring to overcome the prestressing force exerted by its radially projecting ends.
The document EP-A-0 901 759 proposes to conceal the helical spring behind a wall attached to one of the jaws. This solution does not solve the problem of the difficulty of fitting the prestressed spring, and in fact tends to accentuate this difficulty by restricting access to the area occupied by the spring.
The document EP-A-0 847 710 proposes to incorporate the helical return spring in a casing attached between the first perforated lugs. The casing is obtained by assembling a main casing body with a U-shaped cross section, and an end hoop attached to the casing body to extend its second end, leaving an arcuate external peripheral slot for one projecting end of the spring to pass through. The two ends of the resulting casing overlap on the outside edge of the first lugs of the hinge. The hinge lugs of the jaws are therefore, in this embodiment, all the same size, and the first lugs are capped by the casing, which constitutes a tube into which the helical return spring is inserted. The casing therefore provides visual continuity between the first two lugs, concealing the spring to confer on the product an esthetic appearance that is pleasing to the eye.
A first disadvantage is the relatively high cost of manufacturing the two-part casing; another disadvantage is that it is relatively complicated to assemble onto the jaws of the hairstyling device. The casing must be molded from a plastics material, and mass production implies the molding of a series of bodies and hoops on opposite sides of a main sprue to which the bodies and the hoops are joined by secondary sprue. It is possible to separate the bodies from the main sprue by breaking the secondary sprues. However, this is not possible for the end hoops, because they are too small, thinner than the diameter of the main sprue. As a result, after injection molding, the hoops and the bodies remain attached to the main sprue. An additional operation of removing them from the sprue by cutting through the bases of the secondary sprues is therefore required.
Also, a complex mold is required to form the lugs and the holes for assembling the hoop onto the main casing body. Given the very small dimensions of the components of the assembly, there are high risks of the parts of the mold that produce them breaking, and the mold parts must have specific and complex movements.
The components are therefore costly to manufacture. However, they are also complex and costly to assemble: the spring must be inserted into the main casing body, then the hoop fitted to the end of the casing body, and finally the spring tensioned and the casing placed on the first jaw of the hairstyling device. The operation is difficult to automate, and calls for a careful and experienced assembly workforce.
The problems addressed by the present invention are those of concealing the helical return spring of the jaws of a hairstyling device, facilitating mounting the spring on the hairstyling device, reducing the cost of manufacturing the component parts of the hairstyling device, and reducing the cost of assembling the hairstyling device.
The basic idea of the invention is to accommodate the return spring in a casing, which facilitates subsequent assembly of the spring onto the jaws of the hairstyling device, and to use a one-piece casing, with no end hoop, which reduces the difficulty of assembling and the cost of manufacturing the components.
To achieve the above and other objects, a shorter casing is used, only one end of which covers the outside edge of one of the first lugs of the first jaw, while the other end of the casing merely bears against the other first lug of the first jaw without covering it and the other first lug of the first jaw is oversized so that it is continuous with the peripheral face of the casing, which achieves visual continuity and conceals the spring.
Accordingly, in a hairstyling device according to the invention :
a first jaw and a second jaw are hinged together by hinge means enabling them to pivot about a transverse hinge axis between a spread apart position and a close together position,
an elastically flexible wire spring is wound helically around the transverse hinge axis and has two radially projecting ends respectively adapted to bias the first jaw and the second jaw relative to each other toward the spread apart or the close together position,
the hinge means include two parallel first perforated lugs on the first jaw spaced apart by a distance for stability, and two parallel second perforated lugs on the second jaw spaced apart by a distance appropriate for them to engage with respective opposite sides of the first perforated lugs, and a connecting spindle oriented along the transverse hinge axis and passing through the four perforated lugs to connect the jaws,
a casing is attached between the first perforated lugs, retained in a fixed position on the first jaw and forming an axial internal housing containing at least the helically wound portion of the spring, the first radially projecting end of the spring being in fixed bearing engagement with the casing or with the first jaw, the second radially projecting end of the spring exiting the casing to bear functionally against the second jaw and to bias it toward the close together position, the casing having ends with axial openings through which the connecting spindle can pass,
the casing has a peripheral lateral wall with a generally cylindrical outside surface and its first end is extended by a rim on three of its sides to enclose at least in part the outside edge of the corresponding first perforated lug,
the second end of the casing has no rim, and includes an end notch through which the second radially projecting end of the spring passes and in which it can move,
the other first perforated lug of the first jaw is oversized so that its outside edge is substantially continuous with the outside surface of the lateral wall of the casing.
The casing is preferably made in one piece.
In one advantageous embodiment, the second perforated lugs carried by the second jaw are oversized so that their respective outside edges are substantially continuous with the outside surface of the lateral wall of the casing.
The outside surface of the lateral wall of the casing preferably takes the form of a sector of a circular cylinder. This achieves improved visual continuity with the perforated lugs in all relative angular positions of the jaws.
Other objects, features and advantages of the present invention will emerge from the following description of particular embodiments of the invention, which description is given with reference to the accompanying drawings.